The Challenge: Can you solve a medical mystery involving a 38-year-old gardener with a leg rash, numbness and chills? Every month, the Diagnosis column of The New York Times Magazine asks Well readers to sift through a difficult case and solve a diagnostic riddle.

Dr. Karen Jaffe, an obstetrician-gynecologist in Cleveland, was only 48 when she learned she had Parkinson's disease. Four years later, she continues to maintain a full-time medical and surgical practice, even performing ritual circumcisions. ''I'm doing everything I can to stay healthy,'' she...